Liquid petroleum fuels, as butane and octane hydrocarbons, must be vaporized before they can be burned. Vaporizing burners are used to accomplish vaporization by direct heating of the liquid fuel. Examples of vaporizing burners are blow torches, gasoline stoves, wick-type burners and early domestic burners, wherein oil is vaporized from a flame heated plate.
Other types of oil burners use two steps to change the liquid fuel into a combustible form. The steps are (1) atomization of the fuel and (2) vaporization of the atomized fuel. Atomization of the fuel exposes large surface areas of the fuel to air and heat with the result that there is a rapid vaporization of the fuel. The heated air vaporizes the atomized fuel. The atomization is normally accomplished by forcing the liquid fuel through a nozzle and mixing the fuel discharged from the nozzle with heated air. The mixing of the fuel with the air is normally done in the combustion area of the burner. Baumanns et al., in U.S. Pat. No. 3,199,568 disclose an oil heater having a conduit subjected to heat to vaporize fuel in the conduit. The vaporized fuel is mixed with hot air and delivered to a burner plate. Combustion occurs outside the burner plate.
Oil vaporizer and burner units have been designed over the years to vaporize oils prior to combustion of the oil. Makinson disclosed in 1910 in U.S. Pat. No 973,526 an apparatus having a fuel line being heated to vaporize liquid fuel prior to burning. Improvements in Makinson's apparatus are disclosed by Wirth in 1915 in U.S. Pat. No. 1,138,165; Metcalfe in 1922 in U.S. Pat. No. 1,402,243; Rosier in 1927 in U.S. Pat. No. 1,614,045; Astradsson in 1940 in U.S. Pat. No. 2,216,178 and Moench in 1974 in U.S. Pat. No. 3,840,321.
Centrifugal atomizing burners are used to break the liquid fuel into small particles. These burners utilize a rotating disc, cup, or other rotating member for atomizing the liquid fuel. Centrifugal force throws the liquid fuel from the lip of the cup to form a sheet of liquid which quickly breaks into a spray. Low pressure air may be admitted through the space around the cup to produce a wide angle spray. The atomized fuel is heated to vaporize the fuel prior to burning of the vapor fuel.